US4649081A - Magnetic recording medium - Google Patents

Magnetic recording medium Download PDF

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Publication number
US4649081A
US4649081A US06/787,776 US78777685A US4649081A US 4649081 A US4649081 A US 4649081A US 78777685 A US78777685 A US 78777685A US 4649081 A US4649081 A US 4649081A
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Prior art keywords
magnetic recording
modified silicon
recording medium
tape
parts
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Hiroshi Ogawa
Shinji Saito
Chiaki Mizuno
Yasuo Tamai
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Fujifilm Holdings Corp
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Fuji Photo Film Co Ltd
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Assigned to FUJI PHOTO FILM CO., LTD., 210, NAKANUMA, MINAMI-ASHIGARA-SHI, KANAGAWA, JAPAN reassignment FUJI PHOTO FILM CO., LTD., 210, NAKANUMA, MINAMI-ASHIGARA-SHI, KANAGAWA, JAPAN ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: MIZUNO, CHIAKI, OGAWA, HIROSHI, SAITO, SHINJI, TAMAI, YASUO
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    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/62—Record carriers characterised by the selection of the material
    • G11B5/68—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent
    • G11B5/70—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer
    • G11B5/71—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer characterised by the lubricant
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S428/00—Stock material or miscellaneous articles
    • Y10S428/90—Magnetic feature
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/31504—Composite [nonstructural laminate]
    • Y10T428/31652—Of asbestos
    • Y10T428/31663—As siloxane, silicone or silane

Definitions

  • the present invention relates to a magnetic recording medium. More particularly, the invention relates to an improvement of a magnetic recording medium comprising a nonmagnetic support and a magnetic recording layer.
  • a magnetic recording medium basically comprises a nonmagnetic support and a magnetic recording layer provided on the support, the magnetic recording layer comprising a ferromagnetic powder dispersed in a binder.
  • magnetic recording media are used in a variety of forms, for example, an audio-tape, a video-tape, a floppy disk and so on. Naturally, magnetic recording media are required to have various characteristics according to their forms and purposes.
  • the audio-tape such as an audio cassette tape is frequently used for recording music.
  • a magnetic recording medium is required to show excellent electromagnetic conversion characteristics such as satisfactory frequency characteristics and a superb reproducibility of original sounds.
  • a tape should have an improved running property, durability and heat resistance so as to meet the outstanding needs since the magnetic tape-recording medium is now generally employed in automobiles, a cassette tape-recorder with radio and a small-sized tape player.
  • a magnetic recording medium in the form of tape such as a video-tape or an audio-tape should run in contact with a fixed magnetic head, a drum, guide drums and so on. Therefore, a magnetic recording medium needs to have not only excellent electromagnetic conversion characteristics but also a low friction coefficient which enables smooth and stable running for a long period of time. Further, the tape needs to have satisfactory durability and heat resistance, because it should run under a great amount of friction with a magnetic head.
  • the running property of a tape can be improved to a certain extent by incorporating a higher fatty acid, a higher fatty acid ester, a paraffinic hydrocarbon or a silicone oil into a magnetic recording layer.
  • a higher fatty acid, a higher fatty acid ester, a paraffinic hydrocarbon or a silicone oil into a magnetic recording layer.
  • the second object of the invention is to improve the running property of a magnetic recording medium, whereby magnetic conversion characteristics are then improved.
  • a magnetic recording medium comprising a nonmagnetic support and a magnetic recording layer provided on said support, said magnetic recording layer comprising a ferromagnetic powder dispersed in a binder, which is characterized in that said magnetic recording layer comprises at least one modified silicon compound having molecular weight of less than 3,000 and at least one modified silicon compound having molecular weight of not less than 3,000.
  • the modified silicon compound having molecular weight of less than 3,000 is a modified silicon compound having molecular weight in the range of 200 to 2,000 and the modified silicon compound having molecular weight of not less than 3,000 is a modified silicon compound of molecular weight in the range of 5,000 to 100,000.
  • the magnetic recording medium provided by the invention possesses prominently improved magnetic conversion characteristics. Further, the magnetic recording medium of the present invention exhibits an excellent running property and satisfactory heat resistance. The present inventive medium hardly shrinks even when it is kept at high temperatures. The physical durability is also greatly improved.
  • FIG. 1 is a graph showing an example of the characteristic of the output level of the magnetic recording medium of the invention at the distortion rate of 3% at 315 Hz.
  • FIG. 2 is a graph showing an example of the characteristic of the saturated output level of the magnetic recording medium of the invention at 10 KHz.
  • a magnetic recording medium of the invention comprises a nonmagnetic support and a magnetic recording provided on the support.
  • the magnetic recording layer comprises a ferromagnetic powder dispersed in a binder.
  • nonmagnetic support employable in the present invention, and any known nonmagnetic support can be employed.
  • the material of the nonmagnetic support is not particularly limited and can be selected, for example, from polyethylene terephthalate, polypropylene, polycarbonate, polyethylene naphthalate, polyamide, polyamideimide, polyimide and metallic foils such as aluminum foil and stainless steel foil.
  • the thickness of the support film is generally in the range of 3 to 50 ⁇ m and preferably in the range of 5 to 30 ⁇ m.
  • the heat shrinkage ratio of the nonmagnetic support of the invention which is measured along the longitudinal direction (MD) after having been kept for 4 hours at 100° C. under application of no tension should be not higher than 1.2% and more preferably not higher than 1.0%. If the heat shrinkage ratio of the nonmagnetic support exceeds 1.2%, the heat shrinkage ratio of the produced magnetic recording medium also tends to be high, and the deformation of the magnetic recording medium caused by heat shall hinder in some cases the sufficient improvement of the magnetic conversion characteristics and running property.
  • the heat shrinkage ratio measured under the above-mentioned conditions preferably is not higher than 0.7%.
  • the surface roughness (Ra) of the nonmagnetic support is preferably in the range of 0.1 to 0.0001 ⁇ m, more preferably in the range of 0.05 to 0.001 ⁇ m.
  • “Ra” is a center average roughness defined in the Section 5 of JIS-B-0601, at cut-off value of 0.25 mm. If the surface roughness exceeds 0.1 ⁇ m, the produced magnetic recording medium does not have a surface of satisfactory smoothness, and the electromagnetic conversion characteristics are not sufficiently improved in some cases. On the other hand, if the surface roughness of a support is less than 0.0001 ⁇ m, the running property is not satisfactorily improved.
  • the nonmagnetic support may have a back layer (or backing layer) on the opposite side of the side where a magnetic recording layer is coated.
  • the magnetic recording medium of the invention has the above-described nonmagnetic support coated thereupon with a magnetic recording layer comprising a ferromagnetic powder dispersed in a binder.
  • the ferromagnetic powder employable in the present invention is not particularly restricted and can be selected from, for example, ⁇ -Fe 2 O 3 , Fe 3 O 4 , Co-modified iron oxide, alloy powder having iron atom as a major component, modified barium ferrite and modified strontium ferrite.
  • the shape of the ferromagnetic powder normally used is needle shape, grain shape, dice shape, rice shape or plate shape.
  • the size of ferromagnetic powder is normally not greater than 1 ⁇ m, and preferably not greater than 0.5 ⁇ m. Its specific surface area is normally from 20 m 2 /g to 200 m 2 /g, preferably up to 100 m 2 /g.
  • the binder employable in the present invention can be selected from any of resins which are soluble in organic solvents.
  • the resins include cellulose derivatives (e.g., nitrocellulose, cellulose acetate), vinyl chloride/vinyl acetate copolymer resins, (e.g., vinyl chloride/vinyl acetate copolymers, vinyl chloride/vinyl acetate/vinyl alcohol copolymers, and vinyl chloride/vinyl acetate/maleic acid anhydride copolymers), vinylidene chloride resins (e.g., vinylidene chloride/vinyl chloride copolymers, vinylidene chloride/acrylonitrile copolymers), polyester resins (e.g., alkyd resin and linear polyester), acrylic resins (e.g., acrylic acid/acrylonitrile copolymer and methyl acrylate/acrylonitrile copolymer), polyvinyl acetal resin, polyvinyl resin, phenoxy resin, epoxy
  • the magnetic recording layer of the invention can be more hardened.
  • the polyisocyanate compounds which can be used are, for example, adducts of 3 moles of diisocyanate and 1 mole of trimethylol propane (e.g., tolylene diisocyanate, xylilene diisocyanate, hexamethylene diisocyanate), adducts of 3 moles of hexamethylene diisocyanate and buret, isocyanurate compounds of 5 moles of tolylene diisocyanate, isocyanurate adducts of 3 moles of tolylene diisocynanate and 2 moles of hexamethylene diisocyanate and polymer compounds of diphenylmethane diisocyanate.
  • the amount of the binder is generally in the range of 10 to 100 parts by weight and preferably in the range of 15 to 50 parts by weight per each 100 parts by weight of the ferromagnetic powder.
  • the preferred combination of the modified silicon compounds included in the magnetic recording layer of the invention is a combination of a modified silicon compound having molecular weight in the range of 200 to 2,000 and a modified silicon compound having molecular weight in the range of 5,000 to 100,000.
  • the low molecular weight modified silicon compounds mainly contribute to the improvement of running property under the ordinary running conditions.
  • the high molecular weight modified silicon compounds mainly contribute to the improvement of running property after the tape is stored at high temperatures. In this manner, the running properties and heat stabilities are both improved by the incorporation of two or more kinds of modified silicon compounds having different molecular weights in a magnetic recording layer. Further, the magnetic conversion characteristics of a magnetic recording medium are greatly improved.
  • the magnetic recording medium does not show satisfactory heat stability and shows poor magnetic conversion characteristics especially under the circumstances of high temperature and high humidity and after the tape has been stored at high temperatures.
  • the magnetic recording layer includes only the high molecular weight modified silicon compound, the magnetic recording medium does not show satisfactory running property and magnetic conversion characteristics, and further the magnetic recording medium lacks the sufficient lubricity and shows poor durability.
  • the chemical structure of the modified silicon compounds employable in the present invention is not particularly limited.
  • the modified silicon compounds can be selected from those having following chemical structures.
  • R represents a hydrocarbon group having 7 to 17 carbon atomss, and n is an integer of 1 to 3;
  • Modified silicon compound having the formula (8) having the formula (8): ##STR7## wherein R represents either a hydrogen atom or a hydrocarbon group having 1 or 2 carbon atoms, R 1 represents a hydrocarbon group having 1 to 7 carbon atoms, x is an integer of 1 to 50, y is an integer of 1 to 30, z is an integer of 0 to 24, m is an integer of 0 to 3, m 1 is either 0 or 1, and m 2 and m 3 have the relationship that their sum, m 2 +m 3 , is in the range of 3 to 30;
  • the modified silicon compound used in the present invention can also be selected from those disclosed in Japanese Patent Publications No. 57-12417, No. 57-37724, No. 57-37725, No. 57-37726, No. 57-37727, No. 57-37728, No. 57-37729, No. 57-37730, No. 57-37731, No. 57-37732, No. 57-37733, No. 57-37734, No. 57-37735, No. 57-37736, No. 57-40748, No. 57-40749, No. 57-40750, No. 57-40751, No. 57-40752, No. 57-40753, No. 57-40754, No. 57-71521, No.
  • the modifying agent employed to modify a silicon compound is not particularly restricted.
  • the modifying agent can be selected from, for example, fatty acids, alcohols, amines and fluorohydrocarbons.
  • a fatty acid modified silicon compound is preferred, and especially the fatty acid-modified silicon compound having been modified by a fatty acid possessing 12 to 22 carbon atoms are preferred.
  • the fatty acid-modified silicon compounds expressed by the above formulae (1), (2), (3), (4), (5), (9) (10) and (11) are preferred.
  • the amount of the modified silicon compound to be incorporated into the magnetic recording layer is not particularly limited, but the total amount of two kinds of modified silicon compounds is generally in the range of 0.5 to 10 parts by weight, more preferaby in the range of 1 to 5 parts by weight per each 100 parts by weight of the ferromagnetic powder. If the amount is less than 0.5 parts by weight, the electromagnetic characteristics and running property of the magnetic recording medium are not sufficiently improved in some cases. If the amount exceeds 10 parts by weight, the softening of the magnetic recording layer or the blooming of the modified silicon compounds may be caused, and the durability of the magnetic recording medium provided is weakened.
  • the minimum amount of each modified silicon compound is preferably not less than 10 weight percent and more than 20 weight percent of the total amount of all modified silicon compounds used.
  • the magnetic recording layer of the invention may include additives such as a dispersing agent, a lubricant, a stabilizer, an abrasive and an antistatic agent.
  • the dispersing agent employable in the invention are, for example, fatty acids having 12 to 22 carbon atoms (e.g., caprylic acid, capric acid, lauric acid, miristic acid, palmitic acid, stearic acid, oleic acid, elaidic acid, linoleic acid, linolenic acid, metallic soap of alkali metals (e.g., lithium, sodium, potassium) or alkali earth metals (e.g., magnesium, calcium, barium) of the above-mentioned fatty acids, fatty acid amides derived from the above-mentioned fatty acids, aliphatic amine, higher alcohols, polyalkylenoxide alkylphosphate ester, alkylphosphate ester, alkylborate ester, sarcosinates, alkyl ether esters, and other conventional dispersers such as trialkylpolyolefin quaternary ammonium salts and lecithin and surfact
  • the lubricants employable in the invention are, for example, the above-mentioned fatty acids, higher alcohols, fatty acid esters of monovalent fatty acids having 12 to 20 carbon atoms and mono/polyhydric alcohols having 3 to 20 carbon atoms (e.g., butyl stearate, solbitan oleate), mineral oils, animal or vegetable oils, olefin polymers having low molecular weight, ⁇ -olefin polymers having low molecular weight, conventional lubricants (e.g., graphite powder, molybdenum disulfide powder, teflon powder) and lubricants produced for plastics.
  • conventional lubricants e.g., graphite powder, molybdenum disulfide powder, teflon powder
  • the abrasives employable in the invention are, for example, ⁇ -alumina, silicon carbide, chromium oxide, corundum, artificial corundum, diamond, artificial diamond, ⁇ -Fe 2 O 3 , garnet and emery (major components: corundum and magnetite).
  • the average particle diameter of the abrasive is generally in the range of 0.01 to 2 ⁇ m and more preferably in the range of 0.1 to 1 ⁇ m.
  • the antistatic agents employable in the invention are, for example, carbon, natural surfactants (e.g., saponin), nonionic surfactants (e.g., those of alkylenoxide group, glycerols, glycidols), cationic surfactants (e.g., higher alkylamines, quarternary ammonium salts, heterocyclic phosphonium compounds such as pyridine or sulfonium compounds), anionic surfactant (e.g., carboxylic acid, sulfonic acid, phosphate and compounds having acid groups such as sulfuric ester groups and phosphoric ester groups), and amphoteric surfactants (e.g., amino acids, amino sulfonic acid, sulfuric or phosphoric esters of amino alcohols).
  • natural surfactants e.g., saponin
  • nonionic surfactants e.g., those of alkylenoxide group, glycerols, glycidols
  • the magnetic recording medium of the present invention can be produced by the process comprising the steps of first by preparing a magnetic paint (or dispersion) containing the ferromagnetic powder, binder, modified silicon compounds and optional additives such as dispersing agent, lubricant, stabilizer, abrasive and antistatic agent in the conventional organic solvent such as methylethylketone cyclohexane, then applying this magnetic paint onto a nonmagnetic support upon which the magnetic paint is allowed to dry.
  • a magnetic recording layer is formed by applying the magnetic paint directly on a nonmagnetic support, but it is also possible to provide an adhesive layer or a subbing layer between the magnetic paint layer and the nonmagnetic support.
  • the details of the ferromagnetic powder, additives, organic solvents and the method of dispersing have been disclosed in Japanese Patent Provisional Publications No. 52-108 (U.S. Pat. No. 4,135,016), No. 52-804, No. 54-21805 and No. 54-46011.
  • the magnetic recording medium of the present invention can also be prepared by following the procedure reported in the above publications.
  • R represents C 17 H 33 ;
  • the compounds and their molecular weights given above are the major components and molecular weights of the modified silicon compounds.
  • a magnetic paint was prepared by the process comprising the steps of dispersely mixing the components indicated below to yield a paste for 3 minutes using a sand grinder using the batch process, and filtering the resultant mixture using a filter having an average pore diameter of 1 ⁇ m.
  • the magnetic paint was coated on a polyethylene terephthalate film having thickness of 7 ⁇ m (the shrinkage ratio is 1.0%, and Ra is 0.02 ⁇ m upon storing at 110° C. for 4 hours), so that the resultant layer after drying would have thickness of 5 ⁇ m. While the layer was wet, the layer was treated with an electromagnet of 1,000 gauss to impart a magnetic orientation. After drying, the magnetic recording layer was subjected to supercalendering in order to make the surface of the layer smooth. The produced sheet was then slitted into a tape having width of 3.81 mm and incorporated in a heat-resisting half. Thus, a Phillips compact cassette tape was provided.
  • Each magnetic recording layer of a cassette tape prepared in Examples 1 to 4 included an equal amount of each of the modified silicon compound of Compound number [1-1] and molecular weight of 578 and the modified silicon compound of Compound number [2-3] and molecular weight of 14436. The total amount of the modified silicon compounds was different in the examples.
  • Each magnetic recording layer of the cassette tape prepared in Examples 5 to 8 included an equal total amount of the modified silicon compound of Compound number [1-1] and of [2-3], 4 parts by weight for each 100 parts by weight of the ferromagnetic powder. The ratio between the two kinds of modified silicon compounds in the layer was different in examples.
  • the cassette tapes provided showed the output levels (M315) at 315 Hz and 3% distortion, saturated output levels (S10K) at 10 KHz, tape running properties, stain and creaking set forth in Table 1. Also set forth in Table 1 in parenthesis are the tape running properties, stain and creaking of cassette tapes after the tapes were played under a tension of 40 g/cm and stored at 110° C. for 4 hours. Set forth also in Table 1 are the heat shrinkage ratios in percentage along the longitudinal direction of a tape under the above-mentioned conditions.
  • a cassette tape was produced following essentially the same procedure of Example 1 except that the modified silicon compounds were not included.
  • a cassette tape was produced following essentially the same procedure of Example 1 except that 4 parts by weight of the modified silicon compound of Compound number [1-1] alone was used for each 100 parts by weight of the ferromagnetic powder.
  • a cassette tape was produced following essentially the same procedure of Example 1 except that 4 parts by weight of the modified silicon compound of compound number [2-3] alone was used for each 100 parts by weight of the ferromagnetic powder.
  • the cassette tapes provided showed the output levels (M315) at 315 Hz and 3% distortion, saturated output levels (S10K) at 10 KHz, tape running properties, stain and creaking set forth in Table 1. Also set forth in Table 1 in parenthesis are the tape running properties, stain and creaking of cassette tapes after the tapes were played under the tension of 40 g/cm and stored at 110° C. for 4 hours. Set forth also in Table 1 are the heat shrinkage ratios in percentage along the longitudinal direction of a tape under the above-mentioned conditions.
  • the tape running properties were evaluated by the running test using 50 commercial cassette players under the conditions of 60% RH at 25° C. and also by the running test using 100 commercial cassette players under the conditions of 80% RH at 100° C. The results of the evaluation are classified into the following.
  • the creaky sounds observed during the tape running are classified into the following.
  • A none, B: 1 roll, C: 2 to 3 rolls, D: 4 to 5 rolls, and E: above 6 rolls.
  • Cassette tapes were produced following essentially the same procedure of Examples 1 to 8 except that the kinds and amount of the modified silicon compounds added were changed as indicated below.
  • the cassette tapes provided showed the output levels (M315) at 315 Hz at 3% distortion, saturated output levels (S10K) at 10 KHz, tape running properties, stain and creaking set forth in Table 2. Also set forth in Table 2 in parenthesis are the tape running properties, stain and creaking of cassette tapes after the tapes were played under the tension of 40 g/cm and stored at 110° C. for 4 hours. Set forth also in Table 2 are the heat shrinkage ratios in percentage along the longitudinal direction of a tape under the above-mentioned conditions.
  • Cassette tapes were produced following essentially the same procedure of Example 1 except that the kinds of modified silicon compounds (or fatty acids) were changed to those indicated below and their amounts were 4 parts.
  • the cassette tapes showed the output levels (M315) at 315 Hz at 3% distortion, saturated output levels (S10K) at 10 KHz, tape running properties, stain and creaking set forth in Table 3. Also set forth in Table 3 in parenthesis are the tape running properties, stain and creaking of cassette tapes after the tapes were played under the tension of 40 g/cm and stored at 110° C. for 4 hours. Set forth also in Table 3 are the heat shrinkage ratios in percentage along the longitudinal direction of the tape under the above-mentioned conditions.
  • Comparison Example 4 Compound number [1-1]
  • Comparison Example 5 Compound number [1-2]
  • Comparison Example 6 Compound number [3-1]
  • Comparison Example 7 Compound number [5-1]
  • Comparison Example 8 Compound number [5-1]
  • Comparison Example 9 Compound number [6-1]
  • Comparison Example 10 Compound number [7-1]
  • Comparison Example 11 Compound number [9-1]
  • Comparison Example 12 Compound number [10-1].
  • Comparison Example 13 Compound number [2-2]
  • Comparison Example 14 Compound number [2-4]
  • Comparison Example 15 Compound number [9-2]
  • Comparison Example 16 Compound number [11-1].
  • Comparison Example 17 myristic acid
  • Comparison Example 18 oleic acid
  • the output level (M315) at 315 Hz at the distortion ratio of 3% and the saturated output level (S10K) at 10 KHz listed in Table 1 indicate the improved electromagnetic conversion characteristics of the recording tape according to the present invention.
  • the electromagnetic conversion characteristics of the present invention are better than those of the recording tape containing no modified silicon compounds (Comparison Example 1) and better than those of a recording tape having only one modified compound of either low or high molecular weight (Comparison Example 1 and 2).
  • the comparison of the output levels of the comparison examples set forth in Table 2 and the output levels of the comparison examples set forth in Table 3 further evidence that the magnetic recording medium of the present invention possesses electromagnetic conversion characteristics superior to those of a magnetic recording medium having one modified compound either of low or high molecular weight.
  • Tables 1 to 3 also indicate that the recording media of the present invention containing modified silicon compounds of both low and high molecular weight exhibit improved properties in tape running properties, stain, adhesion and creaky sound with the tape running.
  • the properties of the tape according to present invention are examined after storing at 110° C. for 4 hours. A deterioration was hardly observed, and the heat shrinkage ratio along the longitudinal direction was determined to show a low value, less than 4%, showing a satisfactory heat resistivity of the present recording medium containing modified silicon compounds of both low and high molecular weight.
  • Table 3 indicates that the recording media having a modified silicon compound of only low molecular weight tend to exhibit poor heat resistance, and the recording media containing only a modified silicon compound of high molecular weight tend to exhibit poor electromagnetic conversion characteristics. Also, the recording media containing a fatty acid tend to exhibit poor heat resistance.
  • the blooming of modified silicon compounds does not occur, whereby the collection of stain on the recording medium is reduced, and the magnetic head is kept clean.
  • the output levels (M315) at 315 Hz at the distortion ratio of 3% obtained in Examples 3, 5, 6, 7 and 8 and Comparison Examples 2 and 3 are indicated in FIG. 1.
  • the saturated output levels at 10 KHz obtained also in the above are indicated in FIG. 2. From these figures, it has been confirmed that the magnetic conversion characteristics are improved by including 10 weight percentage or preferably 20 weight percentage of one of two kinds of modified silicon compounds in a magnetic recording layer in the case where two kinds of modified silicon compounds are used.
  • the components indicated below were mixed dispersely to yield a paste for 3 minutes by using a sand grinder using the batch process.
  • the magnetic paint was coated on a polyethylene terephthalate film having a thickness of 15 ⁇ m (the heat shrinkage ratio is 0.3% and Ra is 0.002 ⁇ m after storing at 70° C. for 48 hours), so that the resultant layer after being dried would have the thickness of 5 ⁇ m. While the layer was wet, the layer was treated with an electromagnet of 2,000 gauss to give a magnetic orientation. After drying, the magnetic recording layer was subjected to supercalendering in order to make the surface of the layer smooth. The sheet obtained was then slitted into a video tape (VHS type) having the width of 1/2 inch.
  • VHS type video tape having the width of 1/2 inch.
  • Each magnetic recording layer of a video tape prepared in Examples 21 to 24 includes an equal amount of each of the modified silicon compounds of Compound number [1-1] and molecular weight of 578 and the modified silicon compound of Compound number [2-3] and molecular weight of 14336. The total amount of the modified silicon compounds was different in the examples.
  • Each magnetic recording layer of a video tape prepared in Examples 25 to 28 contains the equal total amount of the modified silicon compound of Compound number [1-1] and [2-3], 4 parts by weight for each 100 parts by weight of the ferromagnetic powder. The ratio of two kinds of modified silicon compounds in the layer was different in the examples.
  • the video tapes showed the video outputs, S/N ratios and still characteristics set forth in Table 4.
  • Condition 1 at room temperature
  • Condition 2 at 40° C. and at 80% RH
  • Condition 3 after storing 48 hours at 70° C.
  • a video tape was produced following essentially the same procedure of Example 21 except that the modified silicon compounds were not included.
  • a video tape was produced following essentially the same procedure of Example 21 except that 4 parts by weight of the modified silicon compound of Compound number [1-1] alone was used for each 100 parts by weight of the ferromagnetic powder.
  • a video tape was produced following essentially the same procedure of Example 21 except that 4 parts by weight of the modified silicon compound of Compound number [2-3] was used for each 100 parts of the ferromagnetic powder.
  • a video tape was produced following essentially the same procedure of Example 21 except that myristic acid was used instead of the modified silicon compound.
  • a video tape was produced following essentially the same procedure of Example 21 except that oleic acid was used instead of the modified silicon compound.
  • the video tapes showed the video outputs, S/N ratios and still characteristics set forth in Table 4.
  • Condition 1 at room temperature
  • Condition 2 at 40° C. and 80% RH
  • Condition 3 after storing 48 hours at 70° C.
  • the values for S/N ratio are relative values based on S/N ratio at 10 KHz-4 MHz of Super HG-T-120 (the product of Fuji Photo Film Co., Ltd.), which was obtained upon correcting visual sensitivity, taken as OdB.
  • Jitter set forth in Table 5 were frequency changes at 15750 Hz measured by Jitter Display (the product of Japan Victor Co., Ltd.) and NV-8750 (the product of Matsushita electric Co., Ltd.).
  • Skew was measured by TG5-12U (the product of Shiba Den Co., Ltd.) and NV-8750 (Matsushita Electric Co., Ltd.).
  • Jitter and skew were measured by reproducing an information recorded in the tape kept at 25° C. under the humidity of 60% RH.
  • the video tapes showed the video output, S/N ratios and still characteristics set forth in Table 6.
  • Condition 1 at room temperature
  • Condition 2 at 40° C. at 80% RH
  • Condition 3 after storing 48 hours at 70° C.
  • a video tape was produced following essentially the same procedure of Example 21 except that the above-mentioned alloy powder having Fe as a major component was used instead of the Co-coated bertholide iron oxide, and 4 parts by weight of the modified silicon compound of Compound number [1-1] was used alone.
  • a video tape was produced following essentially the same procedure of Example 21 except the above-mentioned alloy powder having Fe as a major component was used instead of the Co-coated bertholide iron oxide, and 4 parts by weight of the modified silicon compound of Compound number [2-3] was used alone.
  • a video tape was produced following essentially the same procedure of Example 21 except the above-mentioned alloy powder having Fe as a major component was used instead of the Co-coated bertholide iron oxide, and instead of the modified silicon compound, myristic acid was used for Comparison Example 27 and oleic acid was used for Comparison Example 28.
  • the video tapes showed the video output, S/N ratios and still characteristics set forth in Table 6.
  • Condition 1 at room temperature
  • Condition 2 at 40° C. at 80% RH
  • Condition 3 after storing 48 hours at 70° C.
  • the video outputs and S/N ratios set forth in Table 4 and Table 6 clearly indicate the improved electromagnetic conversion characteristics of the magnetic recording media of the present invention.
  • the comparison of examples and comparison examples further evidences that the magnetic recording medium of the present invention containing the modified silicon compounds of both low and high molecular weight processes excellent electromagnetic conversion characteristics. Also the long running period at still mode indicates satisfactory durability of the magnetic recording medium according to the present invention.

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  • Magnetic Record Carriers (AREA)
US06/787,776 1984-10-15 1985-10-15 Magnetic recording medium Expired - Lifetime US4649081A (en)

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JP59216882A JPS6194233A (ja) 1984-10-15 1984-10-15 磁気記録媒体
JP59-216882 1984-10-15

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US4649081A true US4649081A (en) 1987-03-10

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US (1) US4649081A (enrdf_load_stackoverflow)
JP (1) JPS6194233A (enrdf_load_stackoverflow)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5470650A (en) * 1992-08-22 1995-11-28 Basi Magnetics Gmbh Magnetic recording media

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4369230A (en) * 1980-05-28 1983-01-18 Sony Corporation Magnetic recording medium
US4431703A (en) * 1981-11-26 1984-02-14 Sony Corporation Magnetic recording medium
US4469750A (en) * 1982-07-29 1984-09-04 Victor Company Of Japan, Limited Magnetic recording media comprising fluorinated organosilicones in a magnetic layer thereof
US4469751A (en) * 1982-09-21 1984-09-04 Victor Company Of Japan, Limited Magnetic recording media comprising specific types of silicone lubricants in the magnetic layer thereof
US4501800A (en) * 1982-07-29 1985-02-26 Victor Company Of Japan, Limited Magnetic recording media comprising organosilicones in a magnetic layer thereof

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS601623A (ja) * 1983-06-20 1985-01-07 Fuji Photo Film Co Ltd 磁気記録媒体

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4369230A (en) * 1980-05-28 1983-01-18 Sony Corporation Magnetic recording medium
US4431703A (en) * 1981-11-26 1984-02-14 Sony Corporation Magnetic recording medium
US4469750A (en) * 1982-07-29 1984-09-04 Victor Company Of Japan, Limited Magnetic recording media comprising fluorinated organosilicones in a magnetic layer thereof
US4501800A (en) * 1982-07-29 1985-02-26 Victor Company Of Japan, Limited Magnetic recording media comprising organosilicones in a magnetic layer thereof
US4469751A (en) * 1982-09-21 1984-09-04 Victor Company Of Japan, Limited Magnetic recording media comprising specific types of silicone lubricants in the magnetic layer thereof

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5470650A (en) * 1992-08-22 1995-11-28 Basi Magnetics Gmbh Magnetic recording media

Also Published As

Publication number Publication date
JPH0533452B2 (enrdf_load_stackoverflow) 1993-05-19
JPS6194233A (ja) 1986-05-13

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